In a known air distillation installation of this type, the elements constituting the installation are all overdimensioned and can have reduced production regimes, which reduction can reach 40% of the maximum production. It is quite evident that an installation designed to operate at 100% of its capacity, and which functions only at 60% of this capacity, would not be economical.
In a plate column, without overdimensioning, only excess flow rates of 5 to 10% can be accepted. Beyond these values, the diameter of the column, as well as the spacing of the plates, must be overdimensioned to permit a margin greater than 10%.